Pages

Monday, January 31, 2011

It is impossible to die from hypothermia in cold water unless you are wearing flotation, because without flotation – you won’t live long enough to become hypothermic.

Despite the research, the experience, and all the data, I still hear “experts” – touting as wisdom – completely false information about cold water and what happens to people who get in it. With another season of really cold water approaching, I feel compelled to get these points across in a way that will change the way mariners behave out there on (or near) the water.

What follows is the truth about cold water and cold water immersion. I know that you think you know all there is to know about hypothermia already (and maybe you do), but read ahead and see if you aren’t surprised by something.

When the water is cold (say under 50 degrees F) there are significant physiological reactions that occur, in order, almost always.

You Can’t Breath:

The first is phase of cold water immersion is called the cold shock response: It is a stage of increased heart rate and blood pressure, uncontrolled gasping, and sometimes uncontrolled movement. Lasting anywhere from 30 seconds to a couple of minutes depending on a number of factors, the cold shock response can be deadly all by itself. In fact, of all the people who die in cold water, it is estimated that 20% die in the first two minutes. They drown, they panic, they take on water in that first uncontrolled gasp, if they have heart problems – the cold shock may trigger a heart attack. Surviving this stage is about getting your breathing under control, realizing that the stage will pass, and staying calm.

You Can’t Swim:

One of the primary reasons given by recreational boaters when asked why they don’t wear a life jacket, is that they can swim. Listen up, Tarzan; I swam for a living for the better part of my adult life, and when the water is cold – none of us can swim for very long. The second stage of cold water immersion is called cold incapacitation. lacking adequate insulation your body will make its own. Long before your core temperature drops a degree, the veins in your extremities (those things you swim with) will constrict, you will lose your ability control your hands, and the muscles in your arms and legs will just flat out quit working well enough to keep you above water. Without some form of flotation, and in not more than 30 minutes, the best swimmer among us will drown – definitely – no way around it. Without ever experiencing a drop in core temperature (at all) over 50% of the people who die in cold water, die from drowning perpetuated by cold incapacitation.
You Last Longer than You Think:

If you have ever heard the phrase, “That water is so cold, you will die from hypothermia within ten minutes.” then you have been lied to about hypothermia. For that matter you can replace ten minutes with twenty, or thirty, or even an hour, and you’ve still been lied to. In most cases, in water of say 40 degrees (all variables to one side), it typically takes a full hour to approach unconsciousness from hypothermia, the third stage of cold water immersion. But remember, you must be wearing flotation to get this far.

We are all different in this regard, but I once spent an hour in 44 degree water wearing street clothes and my core temperature was only down by less than two degrees (I was not clinically hypothermic). It was uncomfortable to be sure, and I wouldn’t recommend finding your own limit, but it probably would have taken another hour to lose consciousness, and an hour after that to cool my core to the point of no return. The bodies efforts to keep the core warm – vasoconstriction and shivering – are surprisingly effective. The shivering and blood shunting to the core are so effective, that twenty minutes after jumping in (twice the “you’ll be dead in ten minutes” time), I had a fever of 100.2.
Rescue Professionals Think You Live Longer:

There is a good side to the misconceptions about hypothermia. Should you ever be in the water in need of rescue, you can be certain that the Coast Guard is going to give you the benefit of every possible doubt. When developing search criteria – search and rescue coordinators use something called the Cold Exposure Survival Model (CESM): It is a program wherein they enter all the available data about the victim (age, weight, estimated body fat, clothing, etc.) and about the environment (water temp, sea state, air temp, wind) and the software spits them out a number that represents the longest possible time you can survive under those conditions. I plugged my own information into it once and it said I could survive for over 4 hours in 38 degree water wearing nothing but a t-shirt and jeans and no flotation. I can tell you from experience that the CESM is full of it – I’d give me 35 minutes tops – but the error is comforting. If the program that determines how long I might live is going to be wrong – I want it to be wrong in that direction.

Out of the Water is Not Out of Trouble:

I lost count of the number of survivors I annoyed in the back of the helicopter because I wouldn’t let them move. I had a rule – if they came from a cold water environment – they laid down and stayed down until the doctors in the E.R. said they could stand. It didn’t matter to me how good they felt or how warm they thought they were. Because the final killer of cold water immersion is post-rescue collapse. Hypothermia does things besides making everything colder. Victims are physiologically different for awhile. One of the things that changes is called heart-rate variability. The hearts ability to speed up and slow down has been effected. Getting up and moving around requires your heart to pump more blood, being upright and out of the water is also taxing, then any number of other factors collide and the heart starts to flutter instead of pump – and down you go. Victims of immersion hypothermia are two things; lucky to be alive, and fragile. Until everything is warmed back up – out of the water and dry is good enough – mobility comes later.

Did You Learn Anything?:

If you did, then hopefully you’ll use it to make good decisions when it comes to being safe on and around cold water; good decisions like these:

1. When working on deck, wear flotation. This includes, especially, all fisherman in Alaska. I couldn’t find more recent research, but the 31 Alaskan “fell overboard” casualties in 2005 died from drowning, not cold water. Not one of them was wearing flotation. Many couldn’t stay above water long enough for their own boats to make a turn and pick them up…..over a life jacket.
2. If you witness a man overboard – getting the life ring directly to them is critical (vital – step one – must do it). Make certain that all-important piece of safety gear is not just on your vessel, but readily available and not tied to the cradle.
3. When working on deck – wear flotation. I said that already? Well, when I quit reading search reports that end with “experienced” mariners dying because they thought they understood cold water – I’ll come up with better advice.

For more advice about how to handle an accidental immersion into cold water – please watch Cold Water Boot Camp below – it is one of the best 10 minutes on immersion hypothermia ever produced.

Friday, January 28, 2011

Most scuba divers do not learn about carbon dioxide during the open water course. Because the likelihood of carbon dioxide-induced problems is almost zero when proper diving practices are followed, the topic is often skipped over in certification classes.

However, carbon dioxide levels in a diver's bloodstream can rise under certain circumstances, and the effects can be disastrous. This article is not intended to frighten, but merely to inform. When a diver understands the risks of high concentrations of carbon dioxide, he is less likely to engage in behaviors that may predispose him to those risks.
Carbon Dioxide and Breathing:

The body needs a small amount of carbon dioxide for normal body functions. One of these functions is respiration. When a person inhales, he breathes in oxygen which his body metabolizes to create energy. One of the waste products of this metabolic reaction is carbon dioxide, which is eliminated from the body when the person exhales. Interestingly, it is the rising level of carbon dioxide in a person's bloodstream (not the falling level of oxygen) that signals the need for respiration.
How Does Your Body Maintain Safe Carbon Dioxide Levels During a Dive?:
A diver's body is constantly producing carbon dioxide, which it eliminates through exhalation. When a diver requires more energy, such as during moderate exercise, his body breaks down oxygen rapidly to provide that energy at a faster rate. This speeds the production of carbon dioxide. To keep the blood level of carbon dioxide steady, a diver's body increases his respiration rate to eliminate excess carbon dioxide, balancing its production and elimination.
Carbon Dioxide in a Diver's Body Can to Rise to an Unsafe Level:

Any factor that causes the concentration of carbon dioxide in a diver's body to rise to 45 mg Hg and above induces hypercapnia – a potentially dangerous excess of carbon dioxide. There are two situations in which this can happen.

• The concentration of carbon dioxide a diver inhales increases.
• A diver does not eliminate carbon dioxide as quickly as he produces it.
The Dangers of Hypercapnia:

1. Loss of Consciousness.
Carbon dioxide has an anesthetic effect on a diver's central nervous system. If the concentration of carbon dioxide rises to 75 mg Hg (depending upon the person), a diver may lose consciousness. Underwater, loss of consciousness is usually fatal – an unconscious diver generally loses his regulator and drowns.

2. Narcosis
The anesthetic properties of carbon dioxide at elevated concentrations can cause narcosis. Some of the common effects of carbon dioxide narcosis are the slowing of mental processes and the loss of dexterity. Only a very small increase in carbon dioxide levels is needed to produce these effects; carbon dioxide is four times more narcotic than nitrogen. In addition to producing narcosis on its own, carbon dioxide can also amplify the narcotic effects of nitrogen and other inert gasses.

3. Oxygen Toxicity
The human body has a programming glitch. It uses the level of carbon dioxide in the bloodstream to determine how much oxygen the body needs. In normal environments, this works well – as the carbon dioxide level increases, so does breathing rate, carbon dioxide elimination, and oxygen absorption. The higher the level of carbon dioxide, the harder a diver's body works to absorb oxygen. Unfortunately, in scuba diving high levels of oxygen can lead to oxygen toxicity, generally characterized by convulsions that result in drowning. High carbon dioxide levels cue the body to increase oxygen concentrations, speeding the onset of oxygen toxicity.

4. Decompression Sickness
Many hyperbaric physicians now believe that high levels of carbon dioxide may increase the risk of decompression sickness. One scenario is that high carbon dioxide levels interfere with the transport and elimination of nitrogen in the lungs. If the body is working hard to eliminate and exhale excess carbon dioxide, it will not be able to eliminate nitrogen as efficiently as it would if the carbon dioxide were not present. High levels of carbon dioxide lead to elevated levels of nitrogen in the body, which increases the risk of decompression sickness.
Avoid Elevated Carbon Dioxide Levels While Scuba Diving:

The most common behaviors and situations that increase the carbon dioxide concentration in a diver's bloodstream are listed below. By avoiding these situations, a diver nearly eliminates the risk of hypercapnia.

• Improper Breathing Techniques

Hyperventilation: When a diver hyperventilates, he fills only a small portion of his lungs and fails to fully exhale. This creates "dead" air spaces - spaces in the lungs and regulator in which air with high concentrations of carbon dioxide are not fully replaced with normally oxygenated air. For example, the first few mL of air a diver inhales from his regulator is "recycled," air with a high level of carbon dioxide from his previous exhalation. A diver must inhale fully to get past this air and receive fresh air. If a diver does not fully exhale, some of the of the old, carbon dioxide-filled air will remain in his lungs and he will breathe it again with his next breath. The concentration of carbon dioxide in a diver's lungs and regulator "dead" air space increases with each hyperventilated breath, leading to an increase in the level of carbon dioxide in his bloodstream.

Skip Breathing: In an effort to reduce air consumption, many divers hypoventilate or skip breathe. This involves extremely slow breathing. The diver exhales fully and then holds his breath "out", keeping his lungs empty for a period of time before breathing in. Hypoventilation increases the carbon dioxide level in a diver's lungs. Skip breathing can be dangerous because of the risk of hypercapnia.

• Physical Exertion
On land, a person's body adequately deals with the increased production of carbon dioxide during physical exertion by raising respiration rates. Underwater, the excess carbon dioxide is more difficult to eliminate. The breathing resistance of the regulator and the greater density of inspired air at depth make it nearly impossible for a diver to increase his breathing rate to match strong physical exertion. Either the diver begins to hyperventilate, increasing the level of carbon dioxide in his lungs while the carbon dioxide level in his bloodstream also increases, or he maintains a slow and steady breathing rate which is insufficient to eliminate the huge excess of carbon dioxide in his body.

• Deep Diving Without Proper Instruction and Gases
Air and other breathing gases become denser as they compress with depth. The more dense the air, the more difficult it will be for a diver to properly empty and fill his lungs with each breath. The result is retained carbon dioxide in the diver's lungs, similar to the situations listed in "Improper Breathing Techniques" above. This is yet another reason for divers not to go beyond the depth limits of their certification level. Deep diving courses train scuba divers in proper breathing techniques and teaches them about the gas mixtures needed for deep diving. Proper training will help deep divers avoid the risk of hypercapnia.

• Poorly Functioning Breathing Equipment
Regulators that breathe "hard" or increase the resistance of breathing can increase the level of carbon dioxide in a diver's bloodstream. When breathing resistance increases, divers find it hard to draw a full breath and exhale fully. Again, this leads to unintentional hyper- or hypoventilation, which increases carbon dioxide levels. Keep in mind that some regulators will breath easily on shallow dives, but may be inappropriate at greater depths.

• Breathing Gas Contamination
In contemporary scuba diving, it is extremely unlikely to encounter contaminated breathing gas. Strict regulations governing compressor use have helped to standardize tank filling practices. However, if the intake of a compressor is close to the exhaust from an internal combustion engine or other source of carbon dioxide, the air from the tank may contain abnormally high levels of carbon dioxide. While a high level of carbon dioxide may not cause any ill-effects when the tank is tested on the surface, underwater the increased concentration of carbon dioxide may lead to hypercapnia. Carbon dioxide is an odorless and tasteless gas, but other contaminants from exhaust are noticeable. Smell and taste the air from a scuba tank before diving with it. Any unusual findings could indicate that the tank air is contaminated with exhaust or other pollutants which may be accompanied by carbon dioxide. Report strange odors and flavors to the fill station or dive shop and don't dive if you think the tank may be contaminated.

Signs and Symptoms of Hypercapnia:

One of the problems divers face when dealing with elevated levels of carbon dioxide is that the signs and symptoms indicative of an increasing concentration of carbon dioxide may be masked by the dive environment. For example, symptoms such as elevated breathing rate may be attributed to excitement or cold water. Symptoms like headache may be misattributed or absent due to the high partial pressure of oxygen at depth. Unfortunately, this means that the first sign of carbon dioxide toxicity may be sudden unconsciousness. Here are common signs and symptoms of hypercapnia.

Wednesday, January 26, 2011

For the previous post, we talked about certain kinds of non-lethal jellyfish. As for this post, we’ll be identifying the kinds of deadly Jellyfish that you don’t want to meet when you’re down under the sea and what to do if ever you get stung.

The Box Jelly – It’s also known as the Sea Wasp or Chironex Fleckeri. It’s found off the shores of Northern Australia, Papua New Guinea, Malaysia, Indonesia, Philippines, Thailand and Vietnam. This marine animal has a boxy bell head the size of a basket ball, 4 parallel brains [one on each corner], 24 eyes and 60 arseholes.

There are 5,000 deadly stinging cells on each of its 10- 60, two meter long tentacles. They are usually a problem from October to May. They are the most toxic creatures on Earth. These are the symptoms of an attack of the Box Jelly:

- Severe pain

- Headache, nausea, vomiting, diarrhea

- Skin swelling/wounds/redness

- Difficulty breathing, swallowing and speech

- Shivering, sweating

- Irregular pulse/heart failure

Irukandji jellyfish – Irukandji jellyfish are very small, with a bell about one centimeter wide and four tentacles, which range in length from just a few centimeters to up to 35 cm in length. The stingers (nematocysts) are in clumps, appearing as rings of small red dots around the bell and along the tentacles. They are found in Australia.

They are known as Irukandji jellyfish because they cause symptoms known as Irukandji syndrome (a condition that is induced by venomization that is seldom fatal, but if immediate medical action is not taken, within only 20 minutes the victim could go into cardiac arrest and die). They are usually a trouble from November to May, though recently they have been recorded present in all months except July and August. The most common known jellyfish of this type are Carukia barnesi and Malo kingi. Symptoms of an attack:

- Lower back pain, intense headache.

- Muscle cramps and shooting pains, nausea, vomiting.

- Catastrophically high blood pressure.

- Restlessness and feeling of impending doom.

- Death from heart failure or fluid on the lungs.

Of course we won’t leave you with just these symptoms of death and doom. So here’s what you should do when you get stung by one of these deadly Jellies:

- Rinse the area with sea water. Do not scrub or wash with fresh water which will aggravate the stinging cells. Do not pour sun lotion or spirit-based liquid on the area.

- Deactivate remaining cells with a vinegar rinse before removing them; otherwise inactive nematocysts may be triggered. If no vinegar is available use urine – but NOT for Box jelly and Irukandji stings. Ask a mate for a golden shower! Really! Preferably male urine as it’s considered to be more sterile

- Lift off any remaining tentacles with a stick or something similar.

- If cells still linger, dust with flour and carefully scrape off with a blunt knife.

- After all tentacle sections have gone, pain can be treated with a cold pack and/or a local anesthetic such as a sunburn lotion or insect bite treatment that lists ‘ocaine’ as an ingredient.

- If there is continued swelling, or itchiness, apply a light steroid cream e.g. Hydrocortisone eczema cream.

- If muscle spasms persist see a doctor.

Some additional treatment for the Box Jelly.

- Use pressure-immobilization on limbs if possible. e.g. quickly wrap a light bandage above and below the sting (if you can’t get two fingers under the bandage, it’s too tight).

- Immobilize/splint the stung area and keep it at heart level [gravity-neutral] if possible. Too high causes venom to travel to the heart, too low causes more swelling.

- Do not drink alcohol, or take any medicine or food.

Now that you’ve read all these information, I believe it’s still best to remind ourselves of these basic yet very helpful guidelines.

- Take extreme precautions if you have an existing heart condition as Jellyfish deaths are normally attributed to cardiac arrest [or pulmonary congestion]. You are in great danger from the Toxic Boxes’ venomous sting unless treated immediately as the pain is so excruciating that you may go into shock and drown before reaching the shore. So swim with a partner if possible.

- Avoid swimming in the October-May high-jelly season.

- Wetsuits or Lycra ’stinger suits’ offer good protection especially the sophisticated models with hands, neck and head coverage. Feet may be covered by fins or swimming shoes.

- Take notice of warnings! Bathing areas prone to toxic jellies may have safety signs.

Keep your eyes peeled when swimming in areas where the more dangerous variety live (though Irukandji jellyfish are very small and barely visible to see, so accomplish first steps first before relying on this one).

With these in mind and heart I believe you will be able to achieve a more wonderful and wary diving experience. Make sure that you have a healthy heart, because that is the organ that is directly affected by Jellyfish venom. Cardiac arrest is mostly the cause of death by jellyfish. That’s why Will Smith died in the movie 7 Pounds, not because he was electrocuted by some jellyfish (whoops, spoiler alert… haha).

Jellyfish are wonderful creatures, and they will treat you wonderfully too if you treat them and their habitat in the same manner.

Tuesday, January 25, 2011

A dangerous hunt for food, under the sea ice at low tide in northern Canada.

The Inuit of Arctic Canada take huge risks to gather mussels in winter. During extreme low tides, they climb beneath the shifting sea ice, but have less than an hour before the water returns.

The 500 people of Kangiqsujuaq, near the Hudson Strait, go to great lengths to add variety to their diet of seal meat, seal meat and yet more seal meat.

This settlement and a neighbouring community on Wakeham Bay are thought to be the only places where people harvest mussels from under the thick blanket of ice that coats the Arctic sea throughout the winter.

The locals can only do this during extreme low tides, when sea ice drops by up to 12m (about 40 feet), opening fissures through which the exposed seabed - and its edible riches - can be glimpsed. The best time to go is when the moon is either full or brand new, as this is when the tide stays out the longest.

Filmed for the BBC's Human Planet, they lower themselves into these temporary caverns to gather as many fat and juicy mussels as they can before the tide rushes back in.

It is a risky operation. The ice above is no longer supported by water, and it shifts and groans ominously during the harvest.

Often, says photographer Patrice Halley, who has documented this risky practice for years, a group of mussel-gatherers will have no more than a single lantern or flashlight among them.

A look-out keeps watch for the returning tide, but warning shouts cannot be too loud in case the echoes bring down the ice.

Then it's a scramble to get out before the shifting ice closes the escape hole and seawater refills the caverns.

"We all know stories of mussel hunters who didn't make it out in time. If you can't get out, you die," Mary Qumaaluk told the Human Planet team. She subsequently died in a quad bike accident.

Mussel gathering is a tradition that goes back generations in Kangiqsujuaq, on Quebec's Ungava Peninsula. But the locals say it is getting harder to find places safe enough to venture beneath the ice, which freezes later and melts earlier than it did even a few decades ago.

Saturday, January 22, 2011

As per dragondiver:::
"I was on this trip and on this dive. Travis just continued to film as we were all going back to the boat from the arena. Note: we were ALL kneeling at the arena, as told. The mantas were everywhere. Both the bait ball and the other mantas he was shooting were near him because of his lights. Travis doesn't just 'go for the shot'; he﻿ is extremely respectful of the ocean and all that it entails. It was really a fluke incident that was amazingly caught on video by Johnny"

Scientist; author; multiple record holder; Explorer-in-Residence for the National Geographic Society; Time Magazine ‘Hero for the Planet’ in 1998; member of the International Scuba Diving Hall of Fame; member of the Women Divers Hall of Fame; a.k.a. Her Deepness.

“We’ve got to somehow stabilize our connection to nature so that in 50 years from now, 500 years, 5,000 years from now there will still be a wild system and respect for what it takes to sustain us.”

Sylvia Earle, called “Her Deepness” by the New Yorker and the New York Times, “Living Legend” by the Library of Congress, and “Hero for the Planet” by Time, is an oceanographer, explorer, author, and lecturer with a deep commitment to research through personal exploration.

Earle’s work has been at the frontier of deep ocean exploration for four decades. Earle has led more than 50 expeditions worldwide involving more than 6,000 hours underwater. As captain of the first all-female team to live underwater, she and her fellow scientists received a ticker-tape parade and White House reception upon their return to the surface. In 1979, Sylvia Earle walked untethered on the sea floor at a lower depth than any other woman before or since. In the 1980s she started the companies Deep Ocean Engineering and Deep Ocean Technologies with engineer Graham Hawkes to design and build undersea vehicles that allow scientists to work at previously inaccessible depths. In the early 1990s, Dr. Earle served as Chief Scientist of the National Oceanographic and Atmospheric Administration. At present she is explorer-in-residence at the National Geographic Society.

Sylvia Earle is a dedicated advocate for the world’s oceans and the creatures that live in them. Her voice speaks with wonder and amazement at the glory of the oceans and with urgency to awaken the public from its ignorance about the role the oceans plays in all of our lives and the importance of maintaining their health.
Thanks to Diving Almanac and Book of Records
Kathy Dowsett

Friday, January 21, 2011

While Boxing Day shoppers were chasing hot bargains, Fraser Debney and three of his scuba diving friends were into something much colder – the frigid waters of the St. Lawrence River.

For Fraser, who is beginning his third year in the sport, the dive at Cardinal in Eastern Ontario was primarily to test his ability to withstand cold water without the gear normally used in such water temperatures.

“It gave me an opportunity to push the limits of my wetsuit,” said Fraser, who lives in Montreal. “The other three more experienced people had dry suits (preferred for cold-water dives because of their warmth).”

Fraser improvised by wearing a fine thermal type of underwear under his wetsuit. “I found that it works well. It gets wet but still stays warm in that layer (between the wetsuit/underwear and his body).”

He had no problem staying in the water for 25 minutes or more. Unfortunately, almost all that time was spent standing near shore helping the others with their gear because his alternate air source froze open as soon as he entered the water. “The air runs continually and there’s no way to shut it off.”

Fraser aborted his dive but the other three divers went down to the wreck of the Conestoga, a freighter carrying a cargo of wheat that burned and sank in the 1920s. Two of the divers experienced similar problems as Fraser did and had to surface. The fourth was fine.

The dive site was chosen for its “large safety factor.” The Conestoga wreck is the location of many training dives. It’s shallow (the ship is within 20 feet of the surface) and the current is not strong. A bonus in winter is that there are fewer particles in the cold water so visibility is better. This helps underwater photographers capture good wreck pictures.

On Boxing Day the river was especially cold (one degree Celsius), which contributed to the freezing problem. Fraser said a lot of dive gear is designed for southern climates, adding that some will say it is cold-water ready, “but cold to California is different than cold water in Canada.”

There is cold-water gear designed to withstand the conditions but it is more expensive. While Fraser found he could get by in cold water without a dry suit, he also learned the temperature limitations of his regulator. “My local dive shop is going to run an ice diving course and I was thinking of participating. Now I know my equipment would not sustain doing that course.”

Sunday, January 16, 2011

Richard Lang and Judith Selby Lang have been collecting plastic debris off one beach in Northern California for over ten years. Each piece of plastic Richard and Judith pick up comes back to their house, where it gets cleaned, categorized and stored before being used for their art. The couple make sculptures, prints, jewelry and installations with the plastic they find washed up, raising a deeper concern with the problem of plastic pollution in our seas.

Wednesday, January 12, 2011

With sea levels rising, can humans adapt to a more watery world? The Bajau people of South-East Asia live in stilt houses and fish underwater for up to five minutes on one breath. What does this do to the body?

Take a deep breath in - how long until the urge to gasp for air becomes too much? Perhaps it comes after 30 or 40 seconds.

The Bajau people, sometimes known as the sea gypsies of Malaysia and Indonesia, are renowned natural freedivers. Traditionally, they are born, live and die at sea, and fish by diving 20m (more than 65ft) underwater for minutes at a time on one breath.

At this depth, water pressure is almost three times what it is on the surface, squeezing lungs already deprived of oxygen.

Filmed underwater in real time for the BBC's Human Planet, Bajau fisherman Sulbin demonstrates his techniques off the east coast of Sabah, Borneo. Wearing hand-made wooden goggles and armed with a spear, he first prepares himself mentally.

"I focus my mind on breathing. I only dive once I'm totally relaxed," says Sulbin, who goes into a trance-like state before entering the water.

This degree of mind control is crucial, says freediving instructor Emma Farrell, the author of One Breath, A Reflection on Freediving. "You have to be warm and relaxed - you don't want to hyperventilate before taking your last breath."

The mammalian dive reflex - seen in aquatic animals such as dolphins and otters, and in humans to a lesser extent - helps, says Farrell.

"It's a series of automatic adjustments we make when submerged in cold water. It reduces the heart rate and metabolism to slow the rate you use oxygen."

During breath-holding, oxygen stores reduce and the body starts diverting blood from hands and feet to the vital organs.

Our bodies have a way to compensate. Underwater pressure constricts the spleen, squeezing out extra hemoglobin, the protein in red corpuscles that carry oxygen around the body.

"Not enough research has been done to know if it wears off when you're not diving," says Farrell. "But I know people who do a lot of deep training - as Sulbin does - whose blood is like that of people living at high altitude."

In high altitudes, there is less oxygen and so the amount of hemoglobin in blood increases.

Seeing underwater

For most of their history, the Bajau have lived on houseboats, or in stilt houses built on coral reefs - some far from shore. Many report feeling "landsick" on the rare occasions they spend time on dry land.

Thanks to time spent in the water as children when the eyes are developing, the Bajau, in common with other coastal dwelling people, have unusually strong underwater vision.

Their eye muscles have adapted to constrict the pupils more, and to change the lens shape to increase light refraction.

This makes their underwater eyesight twice as strong, according to Anna Gislen, of Sweden's Lund University, who from 2003 has compared the water vision of sea gypsy children of Thailand and Burma with that of European children. A gap that can narrow with training.

One part of the Bajau body that hasn't fared well is the eardrum, which ruptures at a young age, says Human Planet director Tom Hugh-Jones.

"Sulbin's hearing is shot because he doesn't equalize the pressure in his ears as he dives. He's never had formal dive training. He was taught by his father to hold his breath."

There are evolutionary theories - not widely accepted, he adds - that an early ancestor of modern humans had to adapt to a partially aquatic environment. The aquatic ape theory suggests this is why humans are largely hairless and have a subcutaneous layer of fat for underwater insulation, and so are better adapted to swimming than near relations such as the great ape.

But Sulbin and other Bajau divers have little body fat. The wiry frame of these subsistence fishermen may actually help.

A lean physique is more efficient at using oxygen. And having little body fat makes Sulbin less buoyant, able to walk across the reef bed with ease.

"This type of freediving - repeatedly diving to depths of 10 to 20m - carries the greatest risk of decompression sickness," says Farrell. "But you are less likely to get the bends if you are lean, or very well hydrated."

Some Bajau die of the bends from diving - also a risk for compression divers in the Philippines encountered by the Human Planet team.

"Anyone who thinks this is an example of what a non-smoker's lungs can do will be disappointed," says Hugh-Jones. "Sulbin smokes like a chimney. He says it relaxes his chest."

Monday, January 3, 2011

People say that no matter how careful you are with your actions, there will still be moments where you have to face danger. This is Especially true, when, as a scuba diver when you’re deep down under the sea.

One of the common dangers that scuba divers like you and I should be aware of is getting entangled or entrapped. What do we do in order to avoid these situations? How should we deal with it?

When you come to grips with the sea and it won’t let go

The first tip is that you should never dive a wreck or other overhead environment without the proper training and equipment. Common sense, right? Right. But some still do. Just like the soldiers who should not to go into battle without thorough training and suitable equipment, you shouldn’t dive without proper gear and training.

Second, you must approach those wrecks, cavern, fast-moving water, and other entanglement or entrapment hazards with extreme caution. Be wary of your immediate surroundings. Keep alert of anything that might entangle you or otherwise harm you.

Accidents happen

Now, even if you have kept those tips in mind, there may still be times that you will, for some stupendous reason, still get yourself entangled. Just in case, here’s what you do if ever you do get entangled:

The very first thing that you should keep in mind is that you have to stay calm and conserve your air. Be mindful of your breaths and try to make sure that you’re breathing out in minimum because you’d want your air supply to last.

During these kinds of situations, you should use all the possible means to draw any co-diver’s attention to your situation. You may bang on your cylinder with a metallic device like a knife or any metallic object you have with you to draw attention. You should also use an underwater horn or rattle if ever you do have one with you.

Thirdly, you should also consider use a safety sausage or SMB to signal for help.

Your last option would be, if your air supply is already depleted, and you cannot disentangle your equipment, consider ditching your gear and making an emergency ascent to the surface. Do that ONLY when all other option seems bleak.

As mentioned earlier, there just those darned times when accidents happen. So it’s essentially important for you to always be careful of when you’re deep down under the sea. I’m sure that this would be taught by your diving instructor – if not already. And always keep in mind that you should first think of your safety before exploring the beauty of the sea.

Saturday, January 1, 2011

The federal government may add the great white shark, an ocean predator made famous by the 1975 movie Jaws, to the Species at Risk Act.

Great whites swim closer to the shores of Atlantic Canada than most people realize, but they've been on decline for more than 30 years. Their appearance in Jaws raised the sharks' profile but also opened them to greater risk at the hands of humans.

"The movie had the effect of, first of all, making everybody afraid of sharks, of course — and great whites in particular," said Steven Campana, from the Bedford Institute of Oceanography in Dartmouth, N.S. "There was also a move on the part of some recreational fishermen to go out there and catch a shark, a great white, to show their manliness."

Campana is a senior scientist at the Bedford Institute and also heads the Canadian Shark Research Laboratory there.

While there are no accurate numbers for the great white population, scientists agree their numbers are declining.

'They are out there.'— Mike Henneberry, fisher

It's already illegal to kill a great white in Canada, but now the federal government is hoping to give the species greater protection.

"It's really a matter of supporting other international efforts to reduce catches of great whites and somehow limit their by-catch in other fisheries," Campana explained.

Scientists say about 32 great white sharks have been captured in waters off Atlantic Canada in the past 30 years. In most cases, fishermen hauled the sharks up accidentally.
Mike Henneberry and his crew once hauled in a great white while fishing tuna. Mike Henneberry and his crew once hauled in a great white while fishing tuna. (CBC)

Marty Henneberry of Sambro, N.S., said he and his crew hauled in a huge great white while fishing tuna aboard an American ship.

"It took us like an hour-and-a-half to get it up, to visualize, to see what it was," Henneberry told CBC News.

"As it came up, we seen the tail come out of water. We knew it was a shark but wasn't sure what kind, right? I never ever seen a great white myself."

Henneberry explained they put the shark on a winch, but it because it weighted an estimated 3,000 pounds (1,360 kilograms), it was too heavy to hoist aboard.

"It stalled our winch. We got it up to see the head, and it had the triangle teeth, and that's how we identified it," Henneberry said. "They are out there."

Experts say there is no need to panic, however.

Campana said there are about 300 million sharks swimming around the Atlantic Canadian region, but they're far less interested in people than people are in them.

Blog Ping Tool

Sociable

About Me

Welcome to Scuba Scoop!!!

Welcome to my blog!!!! In creating this blog, I thought what would divers like to read about? Maybe some interesting stories about diving, "outside of the box". With this in mind, I started 'Scuba Scoop '. Get the latest Scuba News, updated regularly!!!

Dive Gear

Discount priced dive gear kirkscubagear. Over 1,500 products, everything the divers need. Check out the rest and come back to the best!!!!!!!
www.kirkscubagear.com